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e-pl5 white dots at high iso

Discussion in 'Olympus Cameras' started by tardegardo, May 15, 2013.

  1. tardegardo

    tardegardo Mu-43 Veteran

    375
    Apr 3, 2012
    Rome, Italy
    Hi guys,
    my new e-pl5 behaves strange at high iso; surely from 3200 I can see these white dots especially, (but not only), in black and white. Noise reduction is auto and noise filter is standard. I am not sure but it seems that if I turn noise reduction on these dots look less striking.
    I tried many pixel mapping but nothing changed.

    I don't remember my omd acted this way.

    here is a 100% crop of the dots,
    you can see them especially at left and right of the frame:

    [​IMG][/URL]

    Uploaded with ImageShack.us[/IMG]
     
  2. Photophil

    Photophil Mu-43 Regular

    47
    Nov 24, 2012
    Atlanta Georgia area
    My E-PL5 did the same thing. Check out Pixel Mapping in the manual on page 103. That should fix the problem.
     
  3. tardegardo

    tardegardo Mu-43 Veteran

    375
    Apr 3, 2012
    Rome, Italy
    Hi, thanks for reply,
    if you actually read my post: I did many pixel mapping uselessly...
     
  4. tardegardo

    tardegardo Mu-43 Veteran

    375
    Apr 3, 2012
    Rome, Italy
    anyone else?
    can you, e-pl5 owners, try a test for me?
     
  5. RobWatson

    RobWatson Mu-43 Hall of Famer

    If you look closely you will also see black dots ...

    Even with noise reduction (dark field subtraction) and noise filtering there is some noise that is left and gets by the filters. High ISO only makes this "worse". Clean up in post is fairly easy and if there is an option for a so called "despeckle" filter that would work best with minimal impact on the unaffected regions.

    I see then on E-M5 as well. The warmer the camera the worse these residual bits of noise become. They are very hard to see on white due to the larger signal level and high photon noise level "hiding" the effect. In the dark areas with very low signals and low photon noise these lower level artifacts become more readily visible.

    Either that or your camera is getting ready to explode ...
     
  6. tardegardo

    tardegardo Mu-43 Veteran

    375
    Apr 3, 2012
    Rome, Italy
    Hi there Rob, and thanks for writing,
    forgive please my poor english understanding:
    are you saying that it is normal?
    It's true they are more visible in dark, and disappear in luminous areas.
    Not sure about warm shots though.
    I am doing more tests and I am definitely realizing that it is happening almost only from 3200 onward even more if I underexpose -3.



     
  7. RobWatson

    RobWatson Mu-43 Hall of Famer

    Hi ISO under exposure (or in darker areas) particularly in loner exposures - yup, perfectly normal.

    With noise reduction on auto it should kick in around 1 second exposure (I think that is how auto works) so for exposures in which auto has not actually kicked in then there is no correction! This is why I never use auto - either on or off so at least things are more predictable.

    Each camera is different so the dots (white or black) will show up in different places but for a single camera those dots will be in the same place in every image (the exact same pixel). If your dots are moving around then there is something else going on.
     
  8. tardegardo

    tardegardo Mu-43 Veteran

    375
    Apr 3, 2012
    Rome, Italy
    Well, I am not 100% sure, but in some shots I can tell for sure that the dots are exactly there, same place for all of them. In other shots though I am not that sure: some dots could possibly move, and some appear in different areas.
    But I am relieved by knowing that this all is perfectly normal
    (even if I could be wrong but I don't remember such stuff in OMD).



     
  9. tardegardo

    tardegardo Mu-43 Veteran

    375
    Apr 3, 2012
    Rome, Italy
    Thank you again Rob, you clarified a lot;
    but still waiting for some e-pl5 owner-volunteer who shoots with lens cap on at 3200 ISO and shows me a 200 % crop.
     
  10. elandel

    elandel Mu-43 All-Pro

    Apr 16, 2010
    Milan, Italy
    Today I bought an E-pl5, as soon as possible I'll do the test.
    One thing is sure, I don't know if it is normal but on my D700 it doesn't happen.
     
  11. tardegardo

    tardegardo Mu-43 Veteran

    375
    Apr 3, 2012
    Rome, Italy
    ok, I wait.
    Remember: iso 3200, noise reduction auto and noise filter standard.
     
  12. elandel

    elandel Mu-43 All-Pro

    Apr 16, 2010
    Milan, Italy
    Ok. As soon as I learn to set the menus I'll try.

    For me it's at least 'strange' that this happens, but maybe I'm wrong.
     
  13. tardegardo

    tardegardo Mu-43 Veteran

    375
    Apr 3, 2012
    Rome, Italy
    thank you elandel
     
  14. RobWatson

    RobWatson Mu-43 Hall of Famer

    Don't know how helpful this is ... E-M5 1 sec exposure ISO 2500 with closed aperuture (f22)+lens cap.

    Took two photos - one with NR off and one with NR on. Subtract the NR on image from the NR off image - adjust levels to exaggerate and stuff into jpg.

    The "Difference" image shows what NR removed (plus some noise). Note the obvious pattern - clearly some other form of processing besides a "simple" subtraction.

    <a href="http://minus.com/l99sL93mCZAO3">
    <div align=center>
    [​IMG]"800" height="600"
    </div></a>
     
  15. tardegardo

    tardegardo Mu-43 Veteran

    375
    Apr 3, 2012
    Rome, Italy
    I don't know Rob…
    I am viewing some nightly shots I took with my OMD at ISO 3200 and -3 underexposed. They show no white dot, dark is dark and the moon is bright. But I am not sure e-pl5 would have done as good…



     
  16. tardegardo

    tardegardo Mu-43 Veteran

    375
    Apr 3, 2012
    Rome, Italy
    OMD at ISO 3200 and -3 underexposed.
    Pretty blurred, bad shot, but no white pixel anywhere...

     
  17. elandel

    elandel Mu-43 All-Pro

    Apr 16, 2010
    Milan, Italy
    I have reviewed some night shots with other cameras I have had and no white dots. I'm thinking white dots are not normal.
     
  18. tardegardo

    tardegardo Mu-43 Veteran

    375
    Apr 3, 2012
    Rome, Italy
    Ok, thanks,
    let me see your e-pl5 sample when you have it.
     
  19. elandel

    elandel Mu-43 All-Pro

    Apr 16, 2010
    Milan, Italy
    This is a shot with hood on. The settings are those you said but not -3 underexposure.
    Jpg OOC.
     

    Attached Files:

  20. elandel

    elandel Mu-43 All-Pro

    Apr 16, 2010
    Milan, Italy
    Let me know if the shot is ok, otherwise tell me and I'll try to manage better.
    If you send me your mail I'll send you 4 shots I took.